1. Field of the Invention
The present invention relates to a vehicle wiper for squeegeeing a windshield and the like of an automobile.
2. Description of the Related Art
In vehicle wipers for squeegeeing a windshield and the like of automobiles, there is a so-called tournament type wiper (i.e., a wiper having a hierarchical tree structure) now in general use. This type of wiper has the wiping-ability of even wiping a curvilinear windshield. The curvilinear windshield is thereby wiped completely.
The above tournament type wiper has a wiper blade which includes one rubber blade and a plurality of levers. The levers further include one first lever and a plurality of second levers. The second levers are held to the first lever which in turn is pivotably held to an arm piece of a wiper arm. Furthermore, the rubber blade is held to yoke levers which in turn are held to the second levers. The levers are thus connected successively to each other in a direction normal to the plane of the windshield, i.e., in a height direction of the rubber blade. In addition, the levers are coupled together so as to pivot freely on each joint portion of the levers.
Since a single wiper blade is provided with a plurality of joint portions in this way, the levers are permitted to swing about their connections (i.e. the joint portions) even for a curvilinear windshield, so as to accommodate a curved surface of the windshield. The wiper blade, more precisely, the rubber blade is thereby allowed to firmly squeegee against the surface of the windshield. As a consequence, the windshield can be wiped completely without detracting from the wiping-ability of the rubber blade.
Such a conventional tournament type wiper has the levers connected together in series in the height direction of the rubber blade, as previously described. Accordingly, the tournament type wiper can even cope with a windshield having a high curvature, with the levers being provided with a larger number of the connections (i.e., the joint portions), when desired. However, an increase in the number of the connections of the levers increases a projected area over a front surface of the wiper blade in a moving direction of a vehicle. Thus, air resistance (i.e., drag) and lift increase with the increase of speed of the vehicle.
An increase in drag is undesirable. Consequently, it is necessary to increase the strength of the wiper and use a larger-sized wiper motor. In addition, an increase in lift leads to the lifting-off of the wiper blade, or rather the rubber blade. This precludes the rubber blade from wiping against the surface of the windshield in firm contact therewith. As a consequence, the rubber blade acquires an inferior wiping-ability.
FIG. 13 illustrates a wiper blade 74 in which a first lever 70 is provided with a fin portion 72 in order to prevent the lifting-off of the wiper blade 74 due to the speed of a vehicle. This vehicle wiper is disclosed in Japanese Patent Application Laid-Open No. 62-61862.
With continued reference to the wiper blade 74, FIG. 14 illustrates a cross-sectional view of a mounting portion 70A. The first lever 70 is formed with the mounting portion 70A to permit the first lever 70 to be mounted to a wiper arm. The mounting portion 70A includes a rear wall 70B in order to increase the rigidity of the mounting portion 70A. The mounting portion 70A thereby assumes a substantially rectangular-shaped cross-section.
Accordingly, the rear wall 70B interferes with a flow of air which passes beneath the fin portion 72 in the direction of arrow W of FIG. 14. This interference adversely affects aerodynamic characteristics.
Further, in United Kingdom Patent Application Laid-Open No. GB 2190834 A, the fin is disclosed, which is provided at the wiper blade in order to prevent the lifting-off of the wiper blade when the vehicle travels at high speeds. However, the torsional rigidity and the flexural rigidity of this wiper blade are insufficient.